Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors has continued to advance at a great pace. For example, the demands of higher resolution and lower power consumption have encouraged the further miniaturization and integration of these devices.
Detection of infrared (IR) light is useful in automotive and night vision applications. However, conventional image sensor devices may poorly absorb infrared light due to the band structure of semiconductor materials used in modern microelectronic devices. Even if conventional image sensors can absorb IR light, the semiconductor may need to be sufficiently thick. Additional semiconductor thickness may complicate other fabrication steps and/or reduce performance.
Furthermore, many materials conducive to absorbing IR light are very expensive (either inherently or by virtue of fabrication techniques needed to process the materials), toxic, and/or have lower sensitivity to the visible spectrum. Accordingly, many elements/compounds capable of detecting IR light may not be ideal choices for integration into modern electronic devices.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.